Editor's note: This is the second in a two-day series about the unsolved murder of Lara Plamann, whose body was discovered Oct. 17, 2007. Return to Part I.

GREENVILLE — Months after 30-year-old Lara Plamann was shot to death near her rural Appleton home, the investigation took an odd detour.

In July 2008, the Outagamie County Sheriff's Department turned its attention more than 300 miles away: to St. Paul, Minn. Over the next several years, a trio of detectives racked up nearly $15,000 in county expenses — mostly for their meals and overnight lodging — as they made their way around drug-infested neighborhoods, desperate for information about Plamann's murder.

The Twin Cities represented a risky place to conduct a Fox Valley murder investigation. After all, victim Lara Plamann hadn't lived in St. Paul. She had no friends or enemies there. She was not involved in drugs. She rarely drank. The Wisconsin farm girl who loved horses was slain in a building on her acreage where she lived with Dianna Siveny, her romantic partner of nine years.

The original probe targeting Dianna Siveny as the suspected killer stalled under the direction of Sgt. Mike Jenks of the Outagamie sheriff's office. After nine months, fellow sergeants Jeff Dietzen and Chris Hammen took the case over. They embarked on an effort to link Plamann's slaying to meth addicts and dealers from Minnesota under a murder-for-hire scheme.

Around Valentine's Day in 2013, the persistent detectives thought they finally solved the Plamann murder — only to have their work unravel in the courtroom because of shortcuts and ill-fated risks taken during their investigation.

Investigative missteps

Back in August of 2008, Sgt. Jeff Dietzen and Sgt. Chris Hammen first interviewed Rosie O. Campbell, a single mother of seven and an admitted drug user. She would come to be considered by detectives as one of their most dependable Twin Cities informants, investigative reports reviewed by the Gannett Wisconsin Media Investigative Team showed. During one of the recorded interviews, the detectives told Campbell that they knew her friend Kandi Siveny was involved in a Wisconsin murder. "Yes, she was directly involved," Dietzen declared. "There's no doubt about it." The detectives interviewed Campbell at least a half-dozen times and once they bought her a chicken dinner as a token of their gratitude for her cooperation.

The St. Paul informant lived in Section 8 public housing and lived largely off public aid, according to transcripts. Court records show Campbell frequently smoked both crack cocaine and crystal methamphetamine. She also had a history of mental illness.

By January 2011, Campbell agreed to wear an electronic body wire at the request of the two detectives. They gave her $60 for a taxi ride to a Twin Cities mobile home of a man by the name of Dennis Johnson. "Rosie said she still thinks Dennis is the person who got Kandi the gun," their reports stated.

Hammen and Dietzen tailed the taxi in their unmarked sheriff's vehicle. They parked nearby and listened as Johnson angrily denied getting Kandi Siveny a gun. Then, things went downhill.

Campbell's credibility was soon called into question when she engaged in "sexual acts" with Johnson in his residence, then bought and consumed street narcotics from him, according to the police report. The episode was recorded on audio tape.

Case reopens

For the next two years, the Plamann murder investigation became dormant, police reports reflect. Then, on Feb. 11, 2013, the murder case was rejuvenated when a St. Paul informant, Curtis Walker, 43, called Hammen boasting he just recorded Campbell confessing to murder, reports show. Walker and Campbell were in an on-again, off-again romantic relationship.

Hammen and Lt. Chris Proietti rushed out to St. Paul. The next day, Walker furnished his cellphone. He had in fact recorded Campbell talking about the murder and calling Dianna Siveny "the conspirator." Campbell claimed "the mom wants her put in the ground," according to transcripts, referring to Dianna Siveny.

"I was able to hear Rosie talk about shooting someone," Hammen stated. "Rosie spoke about digging up some money after the shooting. I heard Rosie say she kicked in a door, grabbed someone by the hair and brought them outside. Rosie states she then walked up to her head, point blank range and shot her."

Walker expected a payout for snitching on his girlfriend. He was on the verge of homelessness, he claimed. Hammen and Proietti scrounged together $50 for one night's stay at the Midway Motel for Walker. The next day, Hammen and Dietzen gave Walker another $100 for two more nights' motel stays, plus $50 for food at the nearby Speedway Mini Mart, police reports show.

Kandi Siveny listens to her attorney, Michael Hart, during witness testimony at the Outagamie County Justice Center in 2013.(Photo: File/Post-Crescent Media)

The investigators surmised that Campbell's recorded ramblings were proof she murdered Plamann. By Feb. 14, 2013, Campbell, 38, was thrown in jail. Kandi Siveny, 34, and Dianna Siveny, 53, were arrested the next day. All were charged with first-degree intentional homicide.

Dubious questioning

"You're arrested for the homicide," Hammen told Campbell.

At the Minnesota jail, Campbell buried her head in her hands. "No! No! I didn't do it," she sobbed. "I didn't do anything ... I'm being arrested for a murder that I didn't do."

"We're going to prove you did," Hammen assured her. "We have it on tape. You opened your mouth."

During the interrogation, Campbell insisted Walker's recordings were false. "I lied to Curtis about it just so he wouldn't think I was a wimp," she claimed.

The detectives suggested Campbell's meth dealer, Kandi Siveny, brought Campbell along "as muscle." Campbell did not drive and did not have a vehicle, transcripts show.

"Kandi drives you. We know," Hammen told Campbell.

The detective repeatedly declares Campbell is "going down for this."

"Oh my God," Campbell cries.

Following the detectives cues, Campbell implicates Kandi Siveny as the shooter.

"I chickened out and she said, 'I got this,'" Campbell professed. "Kandi killed that girl and I can remember."

Campbell claimed the following in her interview with detectives:

She and Kandi Siveny spent the entire five-hour drive to the Fox Valley smoking meth.

Kandi's mother left her front porch light on, the signal that Plamann was home.

Kandi parked along State 96 and was on the phone with Dianna Siveny throughout the long drive. "She was getting phone calls from mom on the phone the whole way there and they were talking, but I never get on the phone," Campbell told detectives.

Kandi marched into the house, pointed a gun at Plamann and ordered her into the garage. Kandi's mother wanted the killing done in the shed for "easy clean up."

Kandi went into the shed and pointed a gun at Plamann, who begged, "No, please don't!"

Campbell stood at door of the pole barn and watched. "Rosie states that after the first shot, the girl's hair and head flew back," interview transcripts note.

Five to seven seconds passed. Then came a second shot. Campbell darted back to the car and yelled at Kandi Siveny. "What the (expletive) have you got me into?"

The two women raced back to the Twin Cities — another 300-mile drive. "Rosie told us that she did see blood on Kandi's jacket and arms. Rosie also explains she had some blood on her shoes," reports reflect.

Unfortunately for the detectives, Campbell's confession did not mesh with the key facts and circumstances of the crime.

When asked what the victim wore, Campbell wrongly answered: "A sweater maybe. Maybe red or maroon or something. It was a dark colored one."

Campbell's scenario of the shooting was not logical. There was no sign of a struggle or confrontation. Plamann appeared to be shot by surprise and from behind. The autopsy indicated both gunshots were contact wounds.

It did not matter. Hammen and Dietzen were satisfied with Campbell's confession. They anticipated three murder convictions to result from their detective work in Minnesota.

They ended up with none.

Back in Appleton, their murder-for-hire conspiracy case would fall apart.

Cellphone records

Dietzen and Hammen had obtained Kandi Siveny's cellular phone records through a court subpoena. The records should have disproved Campbell's claim that Kandi and her mother were on the phone constantly during the supposed drive from St. Paul to commit the Greenville murder. There were no such calls, records show.

In 2014, nearly an entire year after the three arrests, Outagamie County authorities handed over Kandi Siveny's cellular phone records to the criminal defense lawyers. Cell tower records put the Minnesota murder conspiracy theory in jeopardy. Kandi Siveny's cellphone records seemed to give her a solid alibi.

Logs showed Kandi Siveny received calls on her phone around 5 p.m. and 6 p.m. on Oct. 17, 2007, from Joe Primeau, a man she knew in St. Paul. She called his phone three times between 6 and 8:15 p.m. All the calls from her phone bounced off the cellular towers in the Twin Cities where she lived, records reflect.

In May of 2014, courtroom testimony revealed the sheriff's investigators had spoken with Primeau, but had not written a report mentioning the conversation. The detectives also had not asked Primeau if he was on the phone with Kandi Siveny around the time of the Wisconsin murder.

"He was not asked that," Hammen testified.

Dan Kaminsky, the Fond du Lac lawyer defending Dianna Siveny, told the judge, "They admitted they talked to Joe Primeau. We only learned about it from our own investigation, not from any reports. Their answer to where's the interview notes, recording or police report for Joe Primeau? We talked to him. We didn't make a report."

Additionally, a woman in St. Paul, Michele Irmen, told investigators she moved into Kandi Siveny's house in St. Paul three days before the murder.

Kaminsky: "You never asked her if Kandi was there with her in Minnesota on Burr Street during the relevant times of October 17 and 18th, did you?"

Kaminsky: "And you never at any time .... went back and attempted in any way to interview any of the witnesses who were on the other end of the phone line with Kandi Siveny's phone to find out who they claim they were talking to?"

"If you're asking, did I go back and ask that question, if they were on the phone with Kandi Siveny? No, I did not," Hammen testified. "If it's not in the narrative, I did not ask that question."

In October 2014, Outagamie County District Attorney Carrie Schneider dismissed murder charges against Campbell, who agreed to plead guilty to vandalizing the car of Andrea Shay, who also had dated Plamann. That incident occurred two months before Plamann's homicide.

This past February and April, murder charges against Kandi Siveny and her mother were dismissed. At the time, Schneider announced "the factual situation and evidentiary picture has changed."

Hammen recently told Gannett Wisconsin Media he does not second-guess his decision not to ask the people calling Kandi Siveny's phone whether they were speaking with her. He said most of the people were drug users or drug addicts so their memory was not reliable.

Hammen remains proud of his work on the case. He does not want to lose control of the case to a different detective or to the state's Division of Criminal Investigations unit.

"I don't think we missed anything and I'm confident in our findings," Hammen said last week.

"Stunned with the glaring holes"

Kandi Siveny's defense lawyer, Dan Sanders of Milwaukee, said it was apparent to him and Kaminsky that Outagamie County detectives were way over their head on the Plamann murder probe and their work was marred by numerous investigative shortcuts and glaring gaps. Time and time again, the key detectives failed to use basic common sense, Sanders said. He has more than 20 years experience as a federal and state criminal prosecutor. Kaminsky previously was the district attorney in Fond du Lac County.

Dan Kaminsky(Photo: USA TODAY NETWORK-Wis)

Last year, the judge heard testimony that Hammen and Dietzen made numerous investigative trips to Minnesota that did not document their investigative activities such as who they interviewed and the gist of those conversations. Hammen also testified that payments were made to various Minnesota informants that were not mentioned in the corresponding police reports. At one pretrial hearing, Outagamie County Judge Nancy Krueger blasted District Attorney Carrie Schneider's Office for numerous trial delays and for failing to provide police evidence to the defense in a timely fashion. On May 13, 2014, the judge announced: "The state was clearly negligent in handling the discovery process here."

Kandi Siveny's defense lawyer told Gannett Wisconsin Media last week: "I was surprised with the investigation. We were just stunned with the glaring holes ... it's just basic law enforcement, from phone records to complete interviews to follow ups on other leads. It's so remarkable that so many leads in this case went untouched. They set their sights on one theory and ignored all others."

Daniel Sanders(Photo: Kohler & Hart Law Firm)

Sanders said Dianna Siveny and the murder victim had a whole circle of friends who were never investigated. These days, the Sivenys are free and living in Minnesota. Campbell is serving a prison sentence at the Taycheedah Correctional Institution for the unrelated car vandalism crime.

"I don't think it was Rosie Campbell or Dianna Siveny or Kandi Siveny," Sanders said. "Dianna Siveny has a no-nonsense demeanor and they take that to mean she's guilty. I want to know the truth. My heart goes out to the (Plamann) family. Really, the ball is in the court of the Outagamie County Sheriff's Office ... It is a cold case. My biggest concern is that there's somebody out there that has never even been looked at."

John Ferak is an investigative reporter for Gannett Wisconsin Media. He can be reached at jferak@gannett.com on Twitter @johnferak